Class HelpfulERB
In: lib/helpful_erb.rb
Parent: Object

Methods

new   result  

Classes and Modules

Class HelpfulERB::Error

Attributes

erb  [RW]  ERB object
filename  [RW]  Template filename
lines_after  [RW] 
lines_before  [RW] 

Public Class methods

new(text, filename=nil, opts={})

Instantiate a new object with ERB text content. For displaying exception backtrace, also specify the filename the ERB content was read from.

Options:

  • :before => Number of lines of context to display before an exception.
  • :after => Number of lines of context to display after an exception.

[Source]

# File lib/helpful_erb.rb, line 26
  def initialize(text, filename=nil, opts={})
    @text = text
    @filename = filename
    @lines_before = opts[:before] || 5
    @lines_after = opts[:after] || 1

    @erb = ::ERB.new(@text, nil, '-')
    @erb.filename = @filename if @filename
  end

Public Instance methods

result(binder=nil)

Return the rendered string produced from the ERB template. Optionally provide the binding context to use. If an exception is caught when rendering the template, raise a HelpfulERB::Error.

[Source]

# File lib/helpful_erb.rb, line 39
  def result(binder=nil)
    begin
      return @erb.result(binder)
    rescue Exception => e
      # Extract filename and line number of exception.
      stack = caller 0
      line_number = nil
      template = @filename
      for frame in e.backtrace
        if frame =~ /^([^:]+):(\d+):in `(render|result)'$/ or frame =~ /^(#{@filename}):(\d+):in /
          template = $1
          line_number = $2.to_i
          break
        end
      end
      unless line_number
        raise Exception.new("Caught ERB error but couldn't find line number in backtrace:\n#{e.backtrace.join("\n")}")
      end

      lines = @text.split(/\n/)

      min = line_number - @lines_before
      min = 0 if min < 0

      max = line_number + @lines_after
      max = lines.size if max > lines.size

      width = max.to_s.size

      msg = "Problem with template '#{template}' at line #{line_number}:\n"
      for i in min..max
        n = i+1
        marker = n == line_number ? "*" : ""
        msg << "\n%2s %#{width}i %s" % [marker, n, lines[i]]
      end
      msg << "\n\n(#{e.exception.class}) #{e.message}"

      raise HelpfulERB::Error.new(msg, e)
    end
  end

[Validate]